1. Field of the Invention
The present invention relates generally to a gooseneck for use in coiled tubing operations. More specifically, the invention describes a pivoting gooseneck incorporating a linkage mechanism that allows for safer, more stable operation.
2. Description of the Prior Art
Coiled tubing operations typically involve at least three primary components. The coiled tubing itself is disposed on a reel and must, therefore, be dispensed onto and off of the reel during an operation. The tubing extends from the reel to an injector. The injector moves the tubing into and out of the wellbore. Between the injector and the reel is a tubing guide or gooseneck. The gooseneck is typically attached or affixed to the injector and guides and supports the coiled tubing from the reel into the injector. Typically, the tubing guide is attached to the injector at the point where the tubing enters. As the tubing wraps and unwraps on the reel, it moves from one side of the reel to the other (side to side). The gooseneck typically has a flared end that accommodates this side to side movement.
In performing a coiled tubing job or operation, the components required for the job (i.e., at least the coiled tubing reel, gooseneck and injector) are transported separately to the wellsite, thereby adding the expense of additional personnel and equipment (e.g., additional trucks). Once on site, the gooseneck must be attached to the injector. This increases set-up time and expense.
One of the drawbacks of the basic gooseneck is that the flared end restricts the side to side movement or motion that can be tolerated by the system. There is an existing modification of the basic gooseneck (known as a xe2x80x9cpivoting gooseneckxe2x80x9d) that swivels or rotates about the centerline of the injector to allow greater side to side movement of the coiled tubing. For ease of description, the gooseneck position wherein its sides are parallel to the sides of the reel (i.e., wherein the coiled tubing is substantially centered on the reel), will be called the mean position or the zero degree position. However, the major drawback of the pivoting gooseneck is that it has a maximum potential energy at the mean position (i.e., a point on the gooseneck structure traces a path of an inverted xe2x80x9cUxe2x80x9d or inverted parabola as the gooseneck moves from side to side). This puts the pivoting gooseneck in unstable equilibrium. This unstable equilibrium has the tendency to push the gooseneck to either side. In certain situations, this tendency may cause the gooseneck to fall off the ends or may cause uneven or irregular motion of the tubing and/or gooseneck.
The gooseneck of the present invention overcomes the drawbacks of the prior art by having a linkage mechanism that results in a minimum potential energy at the mean position (i.e., a point on the gooseneck structure traces a substantially parabolic path as the gooseneck moves from side to side). This ensures that the gooseneck is in stable equilibrium during normal or standard operating parameters. This feature also provides the gooseneck with the tendency to return to a stable, centered position, relative to the injector and the tubing reel, as opposed to prior art devices which tended to xe2x80x9cfall offxe2x80x9d to the side. It should be understood that any suitable design may be used in conjunction with the present invention to allow the gooseneck to trace or maintain a substantially xe2x80x9cupright Uxe2x80x9d path as it tracks the coiled tubing traveling onto or off of the reel.
The linkage mechanism is a four bar type, which consists of two cylinders, wherein the cylinders are each connected, at one end, to one corner of a triangular plate. The third corner of the plate is connected to the gooseneck. The triangular plate is typically positioned such that the third corner (i.e., a point on the gooseneck structure) traces a path of an upright xe2x80x9cUxe2x80x9d as the gooseneck rotates or pivots about to accommodate movement of the tubing as it feeds onto or off of the reel. The rotation of the gooseneck about the center of the injector is typically facilitated by a suitable bearing or other connector on the injector. The triangular plate may slide between two mounting plates, which are also connected or attached to the gooseneck itself.
Another useful feature of the present gooseneck is the incorporation of an overload protection system or mechanism. The system minimizes the possibility of catastrophic failure in the event the gooseneck is overloaded, thereby improving the Safety of the coiled tubing operation. The system typically includes relief valves mounted on the cylinders that transfer the load from the gooseneck to the injector (i.e., the cylinders that form a part of the linkage, as previously described). The relief valves include a pressure sensing device for determining the pressure exerted in each cylinder and may be set to blow or release at a certain pressure, thereby limiting the load on the gooseneck and allowing for energy dissipation in the event of overloading.
The basic gooseneck described in the prior art is generally a one-piece structure that cannot be lowered for tool installation, storage or transportation. The gooseneck of the present invention overcomes this limitation by having a compact folding design that allows the gooseneck to be lowered for tool installation and occupy a decreased space for purposes of storage and transportation. This is achieved by retracting the main cylinders (which support the gooseneck on the injector). As the cylinders retract, the gooseneck pivots about the pin connection at the injector and the gooseneck height is lowered, thus allowing more height for tool installation. The gooseneck may also be formed from a plurality of sections, which may be hinged or otherwise attached to each other such that when the gooseneck is not in use, it may be folded to a decreased, compact size.